Millions of state pensioners will lose out on £646.20 that other pensioners will receive when the next Triple Lock pension boost comes into force.

The Triple Lock is a guarantee that state pensioners’ benefits will be increased each year to account for inflation, in order to maintain pensioners’ spending power at the same level in real terms.

Every new financial year, the state pension must increase by one of three key metrics: CPI inflation, wage growth or a flat 2.5 percent, whichever is highest.

And new figures released this week suggest that wage growth is going to be the determining factor in the Triple Lock next April, with the annual state pension now expected to rise by £629, based on wage growth of 4.1 percent in the latest ONS figure for July and revised now.

The latest wage growth figures would put the weekly state pension up from its current £218.20 a week to £230.30 per week, or £11,975.60 per year, an increase of £629 on the current £11,346.40 this year.

But the old state pension will only go up to £176.45.

It means those on the old basic state pension – so anyone born before April 6 1953 for a woman and April 6, 1951 for a man, is missing out on the full new state pension amount to the tune of £53.85 per week or £2,800.20 across a full year.

Many pensioners do not receive the full state pension and so they will not see the full cash increases. Recent analysis released by Royal London revealed only around half of people receiving the new state pension last year were getting the full weekly amount – and around 150,000 were on less than £100 per week.

Although there are fears for the long term viability of the Triple Lock because of the large and somewhat unpredictable cost to the public purse, Labour have pledged to maintain the Triple Lock for their term in Parliament.

Sir Steve Webb, a partner at consultants LCP warned: “Even a slightly improved pension rise will however leave many pensioners out of pocket in real terms overall next April.